Field of the Invention
The present invention relates to a Rh-based heat-resistant alloy suitable for a member of jet engines, gas turbines and the like, and to a method for manufacturing the same, and particularly relates to an alloy that has heat resistance and oxidation resistance superior to those of conventional Ni-based alloys and can maintain required strength even upon exposure to severe high temperature atmosphere.
Description of the Related Art
As for functional components of gas turbines, aircraft engines, chemical plants, automobile engines, turbocharger rotors and the like and members of a high-temperature furnace and the like, strength under a high-temperature environment and excellent oxidation resistance are required. As this type of high-temperature-resistant materials, Ni-based alloys and Co-based alloys have been conventionally used.
Strengthening mechanism for a Ni-based alloy as a heat-resistant material is basically a precipitation strengthening, which comprising dispersing a γ′ phase (Ni3(Al, Ti)) having an L12 structure as a strengthening phase in the matrix alloy. Since the γ′ phase exhibits inverse temperature dependence where strength increases with an increase in temperature, the phase imparts excellent high temperature strength and high temperature creep characteristics to create a Ni-based alloy suitable for heat-resistant applications such as a rotor blade of a gas turbine and a turbine disk. On the other hand, strengthening mechanism for a Co-based alloy as a heat-resistant material uses solid solution strengthening and precipitation strengthening of carbides. Systems containing a large amount of Cr have excellent corrosion resistance and oxidation resistance and good abrasion resistance, and are therefore used for members such as a stationary blade and a combustor.
More recently, in various heat engines, improvement in thermal efficiency has strongly been required for improving fuel economy and reducing environmental burdens and therefore heat resistance required for heat engine component material has become more severe. Hence, development of a novel heat-resistant material replacing conventional Ni-based and Co-based alloys has been studied.
So far, many research reports regarding novel heat-resistant alloys have been published. The present inventors have also disclosed heat-resistant materials made of the following alloys as new heat-resistant alloys replacing Ni-based alloys: a Co-based alloy in which a γ′ phase intermetallic compound (Co3(Al, W)) having an L12 structure similar to that of a Ni-based heat-resistant alloy is dispersed; and an Ir-based alloy providing a precipitation strengthening effect based on a γ′ phase intermetallic compound (Ir3(Al, W)) having an L12 structure (Patent Literatures 1 and 2).